Thickening



May 27, 1941. KEPPER Re. 21,811 THICKENING, STIRRING, OR AGITATINGAPPARATUS Original Filed July 1a, 1936 4 Sheets-Sheet 1 FIG. I c,

/NVENI'O IQ.-

h'E/VR Y KEPPER May 27, 1941. H, K PPER Re. 21,811

THICKENING, STIRRING, 0R AGITATING APPARATUS Original Filed July 16,1956 4' Sheets-Sheet 2 lag." M

nvrmvron HENRY KEPPEA H. KEPPER May 27, 1941.

THICKENING, STIRRING, 0R AGITATING APPARATIJS Original Filed July 16,.1936 4 Sheets-Sheet 3 INVENT'OR m'E/vnr KEPPER.

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May 27, 19 41;

H. KEPPEYR THICKENING, STIRRING, OR AGITATING APPARATUS 4 Sheets-Sheet 40rigina1 Filed July 16, 1936 [NVE/VTOR HENR) KEPPER mvy.

Reissued May 27, 1941 UNITED STATES" PATENT OFFICE Henry, Kepper,Voorblu'g, Netherlands, assignor to The Don- Company, Inc., New York, N.Y., a corporation of Delaware Original No. 2,122,287, dated June 28,1938, Serial No. 90,965, July 16,1936. Renewed March 12,; 1988.Application for reissue July I, 1939, Se-

rial No. 283,322. In Great Britain July 16,

14 Claims.

This invention relates to thickening, stirring or agitating and likeapparatus for treating settled solids, sludges, pulps or other liquidsor mixtures and maybe employed with particular advantage in thickeningor sedimentation apparatus em-' pioying rotating or revolving rakes orstirring and like devices adapted to thicken the material by theirpassage therethrough while concurrently effecting progressivedisplacement of the settled material preferably towards a dischargeoutlet or outlets.

One of the objects the invention is to provide improved and simplifiedmeans for dealing with overloads in apparatus of the character describedwhen the resistance to movement of the rakes or stirrers increases.

Another object is to provide improved means adapted when the resistanceopposed to movement of the rakes increases, to raise the rakes while atthe same time increasing the driving torque applied to the rakes.

Another object is to provide an apparatus of I the character describedadapted to deliver sludge or other thickened material in which the ratioof.

for apparatus of the character described in whichsistance to motion ofthe rakes. As the inclination of the guide surface is a progressivelyincreasing one it will be seen that as the resistance to motionincreases the rake mechanism is raised upon the guide or cam surfaces toa position where the slope thereof is steeper and consequently the guideis capable of imparting a greater driving torque to the rakes orstirrers with the result that the capacity of the mechanism to clear theoverload is increased.

The rate of increase in the slope of the inclined guides may be constantor it may be varied for different parts of the slope. Thus the lowerpart of the, slope may be steeper, giving a greater increase in thedriving torque for the initial part of the lift than for the latterpart. Alternatively, the upperpart of the slope may be made steeper thanthe lower part so that near the end of the permissible lift the abilityto impart increased driving torque increases at a greater rate. Anautomatic device may be provided to cut out the driving motor when therakes have been raised to the full height permitted.

In a preferred arrangement three (or more) guides are providedcomprising arcuate elements mounted on a driving member or drum andhaving their upper surfaces of the desired progressively increasingslope upon which run rollers mounted on a member from which the rakemechanism is suspended. The guide elements may be adjustably mounted topermit variation of their slope to suit different conditions of working.

relative angular displacement between driving and driven members causesseparating thrust through contacting surfaces adapted to raise the 1rake or similar device while transmitting a constantly increasing torqueto such device.

According to the invention the drive is transmitted to the rotating rakeor stirring devices through relatively movable members one of which isof cam form having a progressively increasing slope so that relativemovement between such members causes the rakes or the like to be raisedor lowered and concurrently therewith effects or permits a progressiveincrease or decrease in the driving torque applied to the rakes.

According to a feature of the invention the rake or stirrer devices aresuspended as by rollers or other sliding engagement means such as slideblocks with one or more inclined guides by the motion of which rotationis imparted to the rakes, the position of the sliding engagement meanson the guide or guides being determined by the weightof the suspendedmechanism and the re- Where such adjustment is provided the engagingrollers must be of extra width to allow for transverse displacement ofthe arcuate guide surfaces when adjusted.

According to a further feature of the invention means are provided forapplying additional load to the rakes and adiustably varying the loadthereon. This may be done for example by loading the suspended part ofthe mechanism in any convenient way as by removable weights. Means mayalso be provided for raising the rakes independently of the automaticarrangement.

According to a further feature, rotatable rake devices and a rotatablescraper device for the discharge are independently mounted so that therakes may be raised in accordance with the load without affecting theposition of the discharge scraper. This may be done by mounting thecurved guide elements upon a vertical shaft carrying the dischargescraper, the rotatable rakes being carried by a hollow shaft or sleevesuspended from the guides. Hand operated means may be provided forlifting the discharge scraper shaft and with it the rotatable rakes.

Other features of the invention will be de-'- scribed hereinafter orpointed out in the appended claims.

Referring to the accompanying drawings Figure 1 is an elevation indiagrammatic form and partly in section of a thickening apparatus forsewage or other sludges or pulps constructed in accordance with theinvention;

Figure la is a sectional elevation of the central portion of theapparatus of Figure 1 showing the supporting and driving mechanism forthe rakes in detail;

Figures 1b and 1c are respectively vertical and a plan view illustrativeof a manner by which a guiding element or cam-shaped member of :Figs. 1and 2 can be supported whereby the sl of the guiding or cam-shapedsurface thereof can be adjusted,

Figure 2 is a diagram showing the principle of the lifting mechanism;and

Figure 3 is a diagrammatic plan view showing the arrangement of thearcuate guides;

Figure 4 is a plan view;

Figure 5 is 'an elevation partly in section of a modified form of the"supporting and driving mechanism for the rakes of a thickener;

Figure 6 is an elevation partly in section of another modified form ofthe supporting and driving mechanism for the rakes of a thickener.

Figures 6a. and 6b are respectively vertical and plan views illustrativeof a manner by which a uiding element or cam-shaved member-thereof canbe supported whereby the slope of the guiding or cam-shaped surfacesthereof can be adjusted.

In carrying the invention into effect according to one convenient modeas applied by way of example to a thickener for sewage or other sludgesor pulps, a settling tank I as shown in Figure 1 is provided with theusual arrangements for introducing the liquid to be treated and fordrawing of]! supernatant clarified effluent, and the settled solidmatter is withdrawn from a central discharge outlet cone 2. A series ofrakes or scrapers 3 of the usual inclined form are mounted uponrotatable arms I carried by a rotatable sleeve element or driven hollowtorque transmitting shaft element} which is adapted for verticalmovement as described hereinafter. A shaft or central shaft element 6 isarranged within the sleeve 5 and carries at its lower end a scraperelement I the purpose of which is to prevent clogging of material in thedischarge cone or outlet 2.

The tank is provided with a transverse beam structure 8 upon which ismounted a superstructure 9 carrying the rotatable rake mechanism.

A gear wheel l driven from a suitable motor through a worm II isrotaltably carried on ball bearings I 2 and has a hub l3 throughwhichthe shaft 6. extends, there being a keying or splined connection betweenthe shaft and hub which permits vertical displacement of the shaft andtransmission of rotational motion thereto. The gear wheel Ill carries asupport ll which affords a bearing for a nut element l engaging with athreaded extension l8 of the shaft I. A handwheel l1 enables the nutelement to be rotated to raise and lower the shaft.

The hollow sleeve 5 which carries the rakes is attached to a drum l8upon the upper edge of which are secured three brackets I! each carry--'to the shaft 5 through the gear wheel II and ing a grooved roller 20.Theserollers run upon inclined guide elements 2| carried by a supportingelement 22 fixedly secured to the shaft I. The guide elements 2| whichare arcuate in plan have their upper edges formed as spiral surfaces ofprogressively increasing slope as shown in Figure 2. The lowest portionof the guide surface terminates in an upwardly curved part 23 whichserves as a stop to prevent the rollers leaving the guide, and thencethe upward slope progressively increases to the point 24. 7

It will be appreciated from the construction described that the sleeve 5and the rakes attached thereto are suspended upon the guide elements 2|and when the rakes are in their lowermost position the rollers 20 willlie against the stop portions 23. Upon applying the drive key connectionIS the guide elements 2| will be moved against the rollers 20 which willtend to lag behind and ride up the guides to a position determined bythe relation between the resistance opposed to the rotation of the rakesand the weight of the mechanism suspended from the rollers, i. e. theweight of the rakes, hollow shaft 5 and the drum IS with itsattachments, This relation is proportional to the slope of the guidesand as this progressively increases so the driv-.

ing torque whichcan be applied to the rakes will increase with the liftof the rakes, or in other words as the load on the rakes increases andthey are lifted proportionately higher, the work done on the solidmaterial by the rakes is increased so that the tank can be cleared ofthe charge outlet 2 clear and preventing the latter from becoming chokedwith solids.

If it is desired to lift the rakes for any reason this may be done byrotating the handwheel H which in turn rotates the nut element mountedthereon. This raises the shaft I and a collar mounted on the lower endthereof engages the sleeve 5 and thus the whole of the rake mechanismmay be lifted. At the same time the scraper 1 is withdrawn from thedischarge cone.

By giving a suitable form to the upper or cam surfaces of the guideelements 2|, any desired operating characteristic may be obtained, suchas is suited to the kind of material being dealt with and the work thethickener is required to perform. Moreover if desired provision mayreadily be made for adjustably varying the slope of the guide surfaces.in various ways but conveniently the arcuate guide elements are pivotedat one end and secured at the other by means such as a bolt engaging ina slot or in a series of bolt holes to give the desired range ofadjustment. Since the guide elements are of arcuate form their camsurfaces will move laterally when adjusted and consequently the rollersmust be made wider than the guide to engage therewith in all positionsof the latter. If desired the rollers may be flanged on one side onlyand have broad treads like-locomotive wheels.

A mode by which the guiding elements 2] are carried-so as to beadjustable with respect to the This may be carried out V supportingelement or carrying plate 22 is illustrated by Figs. 1b and 10.According to these figures, a bracket II is suitably secured--as bywelding to the supporting elementor plate 22 and a bolt and nut 52provide a pivotal means by which the low end of the guiding element iscarriedand secured in place. A second bracket 83 is secured to the plate22: it has a hole for receiving .a bolt 54 that also passes through aslot 56 provided in the deep end portion of the guiding element 2!. Anut on the bolt 54 is relied upon to secure the guiding platein anyadjusted position within the range permitted by the slot II thereof.

/ As previously explained the torque which can be applied to the rakesdepends upon the weight of the parts suspended from the guides and thisaffords a simple way'of adjusting the torque by loading or unloading thesuspended structure. Thus for example suitable weights may be supportedin any convenient manner upon the drum II and by increasing or reducingthe number and/or size of the weights the torque may be adjusted withinthe range available.

Another mode of carrying the invention into effect is illustrated inFigures 4' and 5 which show the driving and supporting mechanism for therakes adapted to be applied to various constructions of thickener orclarifler or similar apparatus. In this example no provision is made forlifting the rakes by hand or for raising the rakes independently of acentre scraper if such is employed. 4

The rakes are mounted upon a vertical shaft which may or may not beprovided with a steady bearing. The shaft is suspended from a spiderframe 28 carrying three grooved rollers 21 which rest on guides 28 ofsimilar form to the guides 2| described in conjunction with the previousexample. These guides are carried by and secured to a large gear wheel29 rotatably carried by ball bearings 20 mounted in a casing 3| which issupported on transverse beams 32. The gear wheel" has a centralhub 33formed as a journal bearing for shaft 26 so that the latter is capableof both vertical and rotational movement with respect to the gear wheel.A motor conveniently mounted on any suitable part of the supportingstructure drives the shaft II which carries a worm meshing with the gearwheel 29. The operation of the device is similar to that of the previousexample and. further description is accordingly unnecessary.

Another-mode of carrying the invention into effect is illustrated inFigure 6 as applied to a thickener 0r-slmilar apparatus of the pedestaltype in which the rake or stirrer mechanism is carried by a drum orequivalent member rotatably suspended from a pedestal upstanding fromthe bottom of the tank. The rake arms (not shown) are mounted in theusual way upon at drum 35 at the upper end of which are secured threebrackets 36 equally spaced thereon. These brackets carry plain rollers31 whichextend inwardly and are adapted to ride upon spiral guideelements 38 which are secured to a second drum 29 of smaller diameterthan the drum 2!. Se-

a worm 41' which is driven from a motor [I mounted on the table 42. g

The mode of operation of the mechanism described above ls similar tothat previously described and it will be appreciated that the guideelements It may be made adjustable if desired. A means by which theguiding element 22 can be adjustably carried from and with respect tothe supporting drum I9 is illustrated by Figs. 6a and 6b. According tothese figures a bolt and nut ll provides a pivotal means by which thelow end of the spiral guiding element ll is carried from the supportingdrum 3!. The high or deep end of the guiding element II is provided withan arc-shaped slot 62 that receives a bolt II.

The nut on the bolt 83 clamps the guiding element in proper adjustmentwith respect to the pended parts of the mechanism as by the addition ofremovable weights so that the torque applied to the rakes may beadjusted.

It is to be understood that the invention may be applied to all types ofthickeners or clariflers including thickeners having more than one com-.partment such as is described in British specification No. 262,479 andalso to stirrers, agitators or sedimentation apparatus of all kindsemploying rotating rakes, stirrers or sludge discharging devices. Theinvention may also'be applied to hydro-separators, i. e., thickenerswhich are fed at a high rate so that separation of fine from coarsematerial is effected by overflowing the finer-material and withdrawingthe coarser particles from the bottom of the tank where they settle.

An important advantage which results from the practice of this inventionis that due to the automatic control of the rakes the thickened materialwhich is withdrawn has an approxicured to the upper end of the drum 2!is an inwardly extending gear ring 40 which rests on ball bearings 4|carried by a supporting table 42 which is secured to the top of thecentral column or pedestal 43. The gear ring ll isprovided with internalteeth which mesh with a pinion II on a vertical shaft 45 carried inbearings on the table 42. A gear 48 on the shaft 45 meshes with ents.

In the operation of the arrangements described. when an undue resistanceis opposed to the rakes due to any cause the rakes are lifted and at thesame time a greater force can be applied to clear the obstruction. Theresult is that a choked or clogged tank may be cleared without thenecessity of closing down the plant by the bringing into play ofautomatic devices for disconnecting the drive or switching out themotor. Thus by the use of the invention more uniform conditions ofoperation may be ensured and the possibility of shut-downs is greatlyminimized, this with the aid of a mechanism which is simple inconstruction and not liable to get out of order.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In or for an apparatus of the character described, a rotatable andvertically movable rake increasing slope arranged so that relativemovement between said members causes the rake or ,like element to beraised or lowered and concurrently therewith eifects or permits aprogressive increase or decrease in the driving torque applied to therake element.

2. In an apparatus of the character described,

. rake or like element.

3. Driving mechanism for an element arranged to rotate about a verticalaxis and adapted to operate upon material in a tank comprising a memberhaving an inclined surface and movable about the said axis, means foradjusting the position of said member to vary the inclination of thesurface thereof, and sliding or rolling engagement means coacting withsaid member and adapted to suspend and carry the said element.

4. An apparatus of the character described comprising a tank, an inletand a discharge outlet therefor, a vertical shaft carrying scraper meansfor the discharge outlet, a sleeve encirgcling said shaft and rotatableindependently thereof carrying rake means for operating upon material inthe tank, a member having an inclined surface attached to and rotatingwith said shaft and means for suspending said sleeve from said inclinedsurface whereby rotation of the shaft will rotate the rake means and"cause the latter to be lifted, independently of the discharge scraper,to a position depending upon the resistance offered to the rake means.

5. An apparatus fortreating solid-bearing liquids or mixtures of liquidsand solids, comprising a tank, inlet and outlet means therefor, anelement rotatable about a vertical axis and adapted to operate uponmaterial in the tank and means for imparting rotation to said element,said means comprising a pair of relatively movable coacting members oneof which is of cam form having a progressively increasing slope arrangedso that relative movement between said members during transmission ofrotation causes the rotatable element to be raised orlowered in the tankand concurrently therewith effects or permits a progressive increase ordecrease in the driving torque applied to the said element.

6. An apparatus for treating solid-bearing liquids or mixtures ofliquids and solids comprising a tank, inlet and outlet means therefor,an element supported on the tank structure for rotation about a verticalaxis, a plurality of arcuate guides carried on said element and havingtheir upper surfaces of progressively increasing slope, means fordriving said element, a vertical member carrying rake or scraper meansoperative within the tank and roller means secured to said verticalmember adapted to run rotation of said guides the rakes or scraper'meanswill be rotated within the tank and concurrently lifted to a positiondetermined by the resistance to rotation. w

with the other member and adapted and arranged for cooperativelyengaging upon said camming surface, said rotary rake member beingsupported by reason of the-eooperative engagement of -said-cam and saidroller in a manner that relative movement between said members causesthe rake element to be raised or lowered, depending upon the raking loadencountered.

8. An apparatus of the character described comprising a tank, a drivenrotary assembly having radial rake arms and a torque transmitting shaftelement rising from and connected with the inner end portions of saidrake arms and rotatable therewith, an annular drive gear element forsaid rake assembly and concentric with said torque transmitting shaftelement, a cam portion associated with one of said concentric elementsand providing a camming surface of upwardly increasing slope, cam rollermeans associated with the other v concentric element and adapted andarranged for cooperatively engaging upon said camming surface, saidtorque transmitting element being supported by reason of the cooperativeengagementof said cam element, and said roller means in a manner thatrelative move-' ment between said annular drive gear element and saidtorque transmitting shaft element will cause said rake arms to be raisedor'.lowered,.depending upon the raking load encountered; annular thrustbearing means for rotatably supporting said annular gear element, asupport stationary with respect to said tank for said annular bearingmeans, and guide means for maintaining concentric and relativelyrotative relationship directly between said torque transmitting shaftelement and said annular gear element.

9. An apparatus according to claim 8 in which said cam element isassociated and rotatable with said gear element. 1

10. An apparatus according the torque transmitting element is rotatablyupon the inclined guide surfaces whereby upon 7. In an apparatus of thecharacter described,-

in combination a driven rotary rake member rotatable about a verticalaxis and mounted for axial movement, a driving rotary member coaxialwith said driven member, a cam element fixedly associated with one ofsaid members and having an inclined camming surface of progressivelyincreasing slope, roller means associated guided by way of said gearsurrounding same.

11. An apparatus according to claim 8 in which the cam roller meanscomprise a plurality of cam rollers substantially equally spaced fromthe axis of rotation of the raking assembly and from one another, and inwhich said cam roller means are supported by a correspondingly equalnumber of cam portions.

12. An apparatus according to claim 8 in which the cam, roller meanscomprise only three cam rollers substantially equally spaced from theaxis of rotation of the raking assembly and from one another, said camrollers being supported by a correspondingly equal number of camportions.

13. An apparatus according to'claim 8 in which the cam portion comprisesa cylindrical crown element concentric and unitary with said gear,surface of an' upwardly progressively increasing slope, roller meansassociated with the other shaft element and adapted and arranged forcooperato claim a in which tively engaging upon said camming surface,said hollow shaft being supported by reason of the cooperativeengagement of said cam element and said roller means in a manner thatrelative movement between said hollow member and said central shaftelement will cause said raking means to be raised or lowered, dependingupon the raking load encountered, whereas the operating position or saidcenter scraper remains unchanged, a l means for driving said centralshaft element.

HENRY KEPPER.

